| 1001 | Omimex Petroleum Inc (De) | Fort Worth, TX 76120 | Oil & Gas Operator | Aug 2020 |
| 1002 | Omni Operating Company | Osage, WY 82723 | Oil & Gas Operator | Sep 2001 |
| 1003 | Oneida Energy Corporation | Tulsa, OK 74137 | Oil & Gas Operator | Jul 2003 |
| 1004 | Open Range Energy LLC | Jones, OK 73049-8744 | Oil & Gas Operator | Mar 2025 |
| 1005 | Opes Production Inc | Buffalo, WY 82834 | Gas Operator | Mar 2015 |
| 1006 | Orion Energy Partners LP | Denver, CO 80202 | Oil & Gas Operator | Nov 2010 |
| 1007 | Oryx Energy Company | Dallas, TX 75221 | Oil & Gas Operator | May 2002 |
| 1008 | Osage Hot Oil Service | Newcastle, WY 82701 | Oil & Gas Operator | Jul 1997 |
| 1009 | Osage Operating Company LLC | Seattle, WA 98133 | Oil Operator | May 2006 |
| 1010 | Osage Partners LLC | | Oil & Gas Operator | Nov 2025 |
| 1011 | Osborn Heirs Company LTD | San Antonio, TX 78217 | Oil & Gas Operator | Sep 2025 |
| 1012 | Ott Inc | Casper, WY 82602 | Oil Operator | Oct 2025 |
| 1013 | Outlaw Oil And Gas LLC | Kaw City, OK 74641 | Oil & Gas Operator | Oct 2025 |
| 1014 | Overland Resources LLC | Greenwood VIllage, CO 80111 | Oil & Gas Operator | Feb 2019 |
| 1015 | Ovintiv USA Inc. | Denver, CO 80202 | Oil & Gas Operator | Dec 2025 |
| 1016 | Oxbow Properties Inc | Centennial, CO 80122-1422 | Oil & Gas Operator | Jan 2025 |
| 1017 | Oxford Exploration Company | Denver, CO 80237 | Oil & Gas Operator | Aug 1995 |
| 1018 | Oxtex Inc | | Oil & Gas Operator | Oct 1989 |
| 1019 | Oxy Petroleum Inc | | Oil & Gas Operator | Jan 1986 |
| 1020 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Dec 2025 |
| 1021 | P & M Petroleum Management LLC | Denver, CO 80202 | Oil & Gas Operator | Oct 2021 |
| 1022 | P & P Producing Inc | Midland, TX 79702 | Oil & Gas Operator | Feb 2015 |
| 1023 | P.O.&G. Operating, LLC | Houston, TX 77057 | Oil & Gas Operator | Dec 2025 |
| 1024 | Pacific Enterprises Oil Co USA | Dallas, TX 75201 | Oil & Gas Operator | Feb 2001 |
| 1025 | Pacific Transmission Supply | | Oil & Gas Operator | Dec 1987 |
| 1026 | Pajaro Energy LLC | Santa Fe, NM 87501 | Oil & Gas Operator | Dec 2023 |
| 1027 | Pal LLC | Gillette, WY 82718 | Oil Operator | Dec 2019 |
| 1028 | Paladin Energy Partner LLC | Denver, CO 80201 | Oil & Gas Operator | Aug 2006 |
| 1029 | Palo Petroleum Inc | Dallas, TX 75360 | Oil & Gas Operator | Dec 2025 |
| 1030 | Pancanadian Petroleum Company | | Oil & Gas Operator | Oct 1989 |
| 1031 | Panther Energy Company III LLC | Tulsa, OK 74136 | Oil & Gas Operator | Jul 2020 |
| 1032 | Paoli Investors LTD | | Oil & Gas Operator | Aug 1985 |
| 1033 | Par Oil Company Inc | Denver, CO 80201 | Oil & Gas Operator | Jun 2003 |
| 1034 | Park Oil Properties LLC | Plano, TX 75025 | Oil Operator | Oct 2019 |
| 1035 | Park Robert E | | Oil Operator | May 1983 |
| 1036 | Parker & Parsley Producing LP | Midland, TX 79702 | Oil & Gas Operator | Oct 1997 |
| 1037 | Pathfinder Energy Inc | Casper, WY 82605 | Oil & Gas Operator | May 2024 |
| 1038 | Patina Oil & Gas Corporation | Denver, CO 80202 | Oil & Gas Operator | May 2016 |
| 1039 | Patrick Petroleum Co. | Jackson, MI 49201 | Oil & Gas Operator | Nov 1993 |
| 1040 | Patriot Energy Resources LLC | Golden, CO 80401 | Gas Operator | Aug 2014 |
| 1041 | Patriot Production LLC | Southlake, TX 76092 | Oil & Gas Operator | Apr 2023 |
| 1042 | PDS Resources LLC | | Oil & Gas Operator | Oct 2025 |
| 1043 | Peabody Natural Gas LLC | Gillette, WY 82718 | Oil & Gas Operator | Nov 2025 |
| 1044 | Peak Powder River Resources LLC | Durango, CO 81301 | Oil & Gas Operator | Oct 2025 |
| 1045 | Peakview Oil Company LLC | Denver, CO 80202 | Gas Operator | Oct 2025 |
| 1046 | Pearce Leonard | Manderson, WY 82432 | Oil Operator | Dec 1999 |
| 1047 | Pearce Mary | | Oil Operator | Dec 1999 |
| 1048 | Pearce Oil Company | Manderson, WY 82432 | Oil Operator | Jun 1999 |
| 1049 | Pease Oil & Gas Company | Grand Junction, CO 81506 | Oil & Gas Operator | May 2000 |
| 1050 | Pecos Development Corporation | San Antonio, TX 78209 | Oil Operator | Aug 1988 |
| 1051 | Pedco Resources Company | Tulsa, OK 74170 | Oil & Gas Operator | Mar 2008 |
| 1052 | Pedry J J | | Oil Operator | Sep 1989 |
| 1053 | Pelican Dome Exploration | Harahan, LA 70123 | Oil & Gas Operator | Jun 1997 |
| 1054 | Pendragon Energy Partners Inc | Midland, TX 79701 | Oil & Gas Operator | Nov 2009 |
| 1055 | Pennaco Energy Incorporated | Gillette, WY 82718 | Oil & Gas Operator | Feb 2021 |
| 1056 | Penneco Exploration Company Of Wyo LLC | Delmont, PA 15626 | Oil Operator | Aug 2021 |
| 1057 | Pennzoil Company | Midland, TX 79710-0090 | Oil & Gas Operator | Mar 2000 |
| 1058 | Petcon Associates LTD | Denver, CO 80202 | Oil & Gas Operator | Sep 2018 |
| 1059 | Peters Walter J | | Oil & Gas Operator | Jul 1991 |
| 1060 | Peterson Energy Management Inc | | Oil Operator | Aug 2010 |
| 1061 | Peterson Energy Operating Inc | Loveland, CO 80537 | Oil & Gas Operator | Nov 2025 |
| 1062 | Petra Petroleum Inc | Littleton, CO 80160-0319 | Oil & Gas Operator | Jun 2005 |
| 1063 | Petral Exploration Inc LLC | Denver, CO 80217 | Oil & Gas Operator | May 2007 |
| 1064 | Petro Energy Inc | Farmington, NM 87499 | Oil & Gas Operator | Sep 2025 |
| 1065 | Petro Search Exploration Corp | | Oil & Gas Operator | May 1993 |
| 1066 | Petro-Canada Resources (USA) Inc | Denver, CO 80202-472 | Oil & Gas Operator | Feb 2010 |
| 1067 | Petro-Hunt Corporation | Dallas, TX 75201 | Oil & Gas Operator | Jun 2003 |
| 1068 | Petro-Hunt, L.L.C. | Dallas, TX 75201 | Oil & Gas Operator | Dec 2025 |
| 1069 | Petro-Lewis Corp. | | Oil & Gas Operator | Feb 1994 |
| 1070 | Petrocarbon Energy Corporation | | Oil Operator | Sep 1996 |
| 1071 | Petrocarbon Energy Trust | | Oil Operator | Sep 1996 |
| 1072 | Petrocorp Incorporated | Tulsa, OK 74170 | Oil & Gas Operator | Nov 2021 |
| 1073 | Petrogulf Corporation | Denver, CO 80202 | Oil & Gas Operator | Dec 2025 |
| 1074 | Petrohawk Operating Company | Houston, TX 77056 | Oil & Gas Operator | Oct 2021 |
| 1075 | Petrolero Corp. | San Antonio, TX 78205 | Oil & Gas Operator | Feb 1998 |
| 1076 | Petroleum Corp Of Delaware The | | Oil & Gas Operator | May 1991 |
| 1077 | Petroleum Inc | Wichita, KS 67202 | Oil & Gas Operator | Oct 2021 |
| 1078 | Petroleum Management LLC | Platteville, CO 80651 | Oil & Gas Operator | Mar 2011 |
| 1079 | Petroleum Products Inc | | Oil Operator | Jun 1996 |
| 1080 | Petroleum Resource Management Corp | Denver, CO 80203 | Oil & Gas Operator | Nov 2025 |
| 1081 | Petrorep Inc | | Oil Operator | Oct 1998 |
| 1082 | Petrox Resources Inc | Meeker, CO 81641 | Oil & Gas Operator | Nov 2025 |
| 1083 | PGC LLC | Newcastle, WY 92701 | Oil Operator | Oct 2023 |
| 1084 | Phillips Petroleum Company | Houston, TX 77251 | Oil & Gas Operator | Mar 2013 |
| 1085 | Phoenix Operating LLC | Denver, CO 80237 | Oil & Gas Operator | Nov 2025 |
| 1086 | Phoenix Production Company | Cody, WY 82414-3607 | Oil & Gas Operator | Oct 2023 |
| 1087 | Phoenix Resources Co | | Oil & Gas Operator | Jun 1984 |
| 1088 | Pine Haven Resources LLC | Boulder, CO 80305 | Oil Operator | Nov 2025 |
| 1089 | Pine Ridge Petroleum LLC | Moorcroft, WY 82721 | Oil Operator | Nov 2025 |
| 1090 | Pinedale Energy Partners Operating LLC | Tulsa, OK 74105 | Oil & Gas Operator | Apr 2021 |
| 1091 | Pinedale Investment Inc | Pinedale, WY 82941 | Oil & Gas Operator | Nov 2025 |
| 1092 | Pioneer Exploration, LLC | Houston, TX 77090 | Oil & Gas Operator | Nov 2025 |
| 1093 | Pioneer Natural Resources USA Inc | Irving, TX 75039 | Oil & Gas Operator | Sep 2025 |
| 1094 | Pioneer Oil & Gas | South Jordan, UT 84095 | Oil & Gas Operator | Jan 2014 |
| 1095 | Pittencrieff America Inc | Abilene, TX 79608 | Oil & Gas Operator | Feb 2003 |
| 1096 | Pivonka Investments LLC | | Oil & Gas Operator | Oct 2025 |
| 1097 | Plains Petroleum Operating Co | Denver, CO 80202 | Oil & Gas Operator | Dec 2014 |
| 1098 | Planet Associates Inc | Denver, CO 80218 | Oil Operator | Dec 1994 |
| 1099 | PML Operating LLC | | Oil Operator | Oct 2025 |
| 1100 | Poc-I LLC | Casper, WY 82605 | Oil & Gas Operator | Nov 2025 |